The invention relates to refrigerators, and in particular to two-temperature refrigerators, provided with a single compressor cooling arrangement.
More particularly, the invention relates to refrigerators having a compressor-cooling arrangement whose cooling circuit, provided with a condenser, a flow restrictor and connecting conduits, has at least two evaporator sections arranged in the flow path of its cooling medium, with the first evaporator section being associated with a colder compartment and the second evaporator section being associated with a warmer compartment, further provided with a regulator device which intermittently turns the compressor on and off in dependence upon the temperature in the warmer compartment, with the regulator device turning on and off both the compressor current path and a heating element for an accumulator connected upstream of the flow restrictor, with turn-on of the accumulator heating element causing liquid cooling medium to be driven out of the accumulator and into the second evaporator section.
With refrigerators of this type it has been suggested to arrange in the cooling circuit between the condenser and the flow restricting arrangement, for example a capillary tube arrangement, a heatable accumulator provided with a heating element which is turned on simultaneously with the compressor, and from which, when the heating element is energized, cooling medium in liquid form is driven into the evaporator section associated with that cooling compartment which is maintained at the higher average temperature. This evaporator section is arranged in the flow path of the cooling medium downstream of the evaporator section associated with the lower-temperature cooling compartment. The operation of the compressor and of the heating element for the accumulator is controlled by means of a regulator provided with a sensor for sensing the temperature of the evaporator associated with the higher-temperature cooling compartment, with different circuit connections being made and broken in dependence upon the setting of the regulator. As a result of the heating of the accumulator, some of the cooling medium stored therein in liquid form evaporates and, due to the resulting volume increase the remaining liquid cooling medium is very suddenly expelled from the accumulator, thereby filling the evaporator of the warmer compartment with cooling medium in liquid form. In this way, the entire inherent cooling power is made available, both upon turning on of the compressor and upon heating of the evaporator associated with the warmer compartment.
Experience has indicated that a refrigerator provided with such a cooling system will operate in a trouble-free manner, so long as temperatures considerably below the freezing point are maintained in both refrigerator compartments, for example as is the case with freezer chests.
Attempts have been made to employ such refrigeration systems, which have been successfully used in freezer chests, in so-called two-temperature refrigerators. A two-temperature refrigerator is comprised of one compartment maintained at a temperature which is not to rise above the freezing point, and a second compartment which is maintained at a higher temperature; if the second compartment is provided with a fully automatic antifrost arrangement, then the temperature of the second compartment is to be maintained at a value just slightly above the freezing point. In particular, this is because the monitoring of the automatic defrosting of the higher-temperature compartment cannot be performed in a trouble-free manner, and in certain circumstances the temperature of the lower-temperature compartment rises above the highest permissible value. For a two-temperature refrigerator, it may for example be desired to maintain the temperature in the lower-temperature compartment always below -18.degree. C during operation, while at the same time providing for the higher-temperature compartment a completely automatic antifrost defroster arrangement for the associated evaporator. When the known refrigeration system is employed, these temperature relationships cannot be reliably realized.